Internally there is only one shared instance of media player in OS. When the app is using it OS sends notifications to the app so that the app can remember the play position. When another app e.g. Xbox music or Pandora app is launched while iPodcast app is running in background OS will take away the media player from iPodcast and let another app use it. However it doesn't notify iPodcast that it's being stopped. So app never gets chance to save its play position. The workaround is to pause the playback via either volume control button or launching iPodcast app before you switch another app. v3.5 has this issue fixed.